No.413.] NORTH-AMERICAN INVERTEBRATES. 391 
, oS. rugosa Linn. 
Trophosome : Colony small, simple, or sparingly and irregularly branched ; 
stems annulated. Hydrothece crowded, strongly annulated transversely, 
and with four marginal teeth 
Gonosome : Gonangia large, ovate, strongly annulated, and with a four- 
toothed aperture. 
2, S. gayi Lamx. 
Trophosome : Stems erect, with alternate branches, somewhat obliquely 
jointed. Hydrotheca somewhat urn-shaped, one to each internode, usually 
wrinkled, and with narrower, diver- 
gent, four-toothed aperture. 
Gonosome : Gonangia elongate, 
42999.  ovate, tapering toward the small, 
of two-toothed aperture. Usually 
S strongly annulated in upper por- 
tion, the lower smooth. 
3, S. tricuspidata. 
Trophosome: Stems slender, 
Fic. 27.—Diphasia fallax Johnst. (After Hincks.) a, 9 gonangium of same (enlarged). 
alternately branched, often bipinnate near the ends. Hydrothecæ cylin- 
drical, prso slightly everted, with a three-toothed orifice 
Gonosome : Gonangia large, with strongly transverse ridges and with a 
plain, PORE saai opening. 
Diphasia Ag. 
, D. fallax Johnston (Fic. 27). 
Trophosome : Stems thick, sparingly branched, branches alternate, often 
terminating in tendril-like bodies. Hydrothece short, tubular, with upper 
Part slightly divergent, and with wide, smooth orifice. 
